ARCO staging (2019 revised)
Trauma and orthopaedics
Also known as: ARCO-Klassifikation (Hüftkopfnekrose) · ARCO evrelemesi (femur başı osteonekrozu) · ARCO staging of osteonecrosis of the femoral head (2019 revision)
What it is for
Stages osteonecrosis (avascular necrosis) of the femoral head from plain radiographs and magnetic resonance imaging (MRI); computed tomography (CT) may help to show a subchondral fracture.
Classification
| Category | Description |
|---|---|
| Stage I | radiograph normal; MRI abnormal (low-signal band around the necrotic area on T1-weighted images) or bone scan positive. |
| Stage II | radiograph abnormal (subtle osteosclerosis, focal osteoporosis or cystic change) without subchondral fracture, fracture in the necrotic zone or flattening of the head. |
| Stage IIIA (early) | subchondral fracture or fracture in the necrotic zone on radiograph or CT, with femoral head depression of 2 mm or less. |
| Stage IIIB (late) | as IIIA but with femoral head depression of more than 2 mm. |
| Stage IV | radiographic osteoarthritis: joint space narrowing, acetabular changes and/or joint destruction. |
| Note | The size and location of the necrotic lesion are no longer part of the stage and are described separately. Older systems such as Ficat-Arlet and Steinberg are still seen in reports. |
Source
The 2019 Revised Version of Association Research Circulation Osseous Staging System of Osteonecrosis of the Femoral Head
ARCO (Association Research Circulation Osseous) · J Arthroplasty 2020;35:933–940 (Yoon BH, Mont MA, Koo KH et al.)
DOI: 10.1016/j.arth.2019.11.029
PMID: 31866252
- Edition
- 2019 revised ARCO staging (published 2020); old stage 0 removed, stage III split into IIIA/IIIB
- Checked on
Summary of the published classification in our own words. Not a substitute for the original publication.
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